Hexbyte Glen Cove How to stick sensors to skin without adhesive thumbnail

Hexbyte Glen Cove How to stick sensors to skin without adhesive

Hexbyte Glen Cove

Credit: Binghamton University

Imagine if you could attach something to your skin without needing glue. A biosensor, a watch, a communications device, a fashion accessory—the possibilities are endless. Thanks to a discovery at Binghamton University, State University of New York, that time could be closer than you think.

Associate Professor Guy German and Zachary Lipsky, Ph.D. ’21, recently published research in the journal Acta Biomaterialia that explores how human can control the way cracks form and why tensometers offer imprecise results when measuring the mechanical properties of biological tissues.

Along the way, Lipsky developed a method to bond human skin to rubber-like polymeric materials without an adhesive. Originally a way to make their experiments easier, he and German understood they had made a significant discovery.

“Zach came in one day and said, ‘Yeah, I did it,'” German said. “I was like, ‘How on Earth did you do that? Did you use a glue?’ Because we’d need to account for the mechanical properties of the glue as well. And he said, ‘No, I just stuck it.’ We looked and said: Has this ever been done before? Never been done. So we’re really happy on that front.”

An invention disclosure for the technique has been filed, which could lead to a patent on what he calls “a very simple technique” that could revolutionize biotech.

“I didn’t know we’d end up there, but that’s sometimes how science works,” German said with a laugh.

The study that spawned the discovery, titled “The Precision of Macroscale Mechanical Measurements is Limited by the Inherent Structural Heterogeneity of Human Stratum Corneum,” started with German’s roots in and his interest in testing the validity of Hooke’s law to .

“We thought, if we use these standard testing techniques to measure the mechanical properties of tissue, especially skin tissue, is it reporting the right values?” he said. “No one’s really ever validated it.”

Developed by 17th-century British physicist Robert Hooke, the law states that the force needed to extend or compress a spring by a distance is proportional to that distance. More generally, researchers can use this law to measure the stiffness of different materials as well as how much energy it costs to break them.

“It got me thinking that, in , you can measure how stiff metals and ceramics are. But what about skin?” German said. “Metals or ceramics have a composition that is fairly uniform, but skin and other tissues have a complex and heterogeneous structure with microscale cells connected by cell-cell junctions. The outer layer of skin also exhibits a complex topographical network of microchannels, which are visible if you look at the back of your hand.”

He and Lipsky bonded skin samples to a piece of polydimethylsiloxane (PDMS), a rubber-like material commonly used in bioengineering and biomedical devices. The samples were then stretched. A modified traction force microscopy technique was then used to quantify changes in the mechanical loads imparted by the skin on the adherent substrate.

“As the skin expanded, a little crack would grow, and we can measure how much energy it required to grow it by a certain length,” German said. “Typically to measure the energy cost of rupture in mechanical engineering you get two grips, you pull and it splits. You measure the force and displacement and quantify the energy. But this assumes that the material is homogeneous—compositionally the same everywhere. What we found out was that cracks in the skin’s outer layer propagate in a very, very weird way.”

The cracks propagate along the topographical microchannels. This elongates the overall path of the crack, increasing the energy it costs to break the tissue. The discovery can be extrapolated to explain the behaviors of other human tissues.

“Because of the heterogeneous structure of skin, it also means that the crack path becomes a lot more random. That’s why you get such variability in macroscale tensometer measurements of skin,” German said, “because even though you get the skin from exactly the same source at exactly the same age, the sample-to-sample variability is so high because the crack paths deviate.”

More information:
Zachary W. Lipsky et al, The precision of macroscale mechanical measurements is limited by the inherent structural heterogeneity of human stratum corneum, Acta Biomaterialia (2021). DOI: 10.1016/j.actbio.2021.05.035

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Hexbyte Glen Cove Startup develops yeast-based COVID-19 diagnostic test thumbnail

Hexbyte Glen Cove Startup develops yeast-based COVID-19 diagnostic test

Hexbyte Glen Cove

Based on a reaction between yeast and the novel coronavirus, the test will rapidly detect the presence of SARS-CoV-2 in saliva and will be available by mid-2021 Credit: BIOinFOOD

Incubated at the University of Campinas (UNICAMP) in the state of São Paulo, Brazil, and supported by São Paulo Research Foundation- FAPESP’s Innovative Research in Small Business Program (PIPE), BIOinFOOD is a startup that is developing a rapid COVID-19 diagnostic test based on a patent application filed by students at UNICAMP’s Genomics and Bioenergy Laboratory.

The is based on a biosensor consisting of a genetically modified brewer’s (Saccharomyces cerevisiae), which changes color if human ACE2 receptor expressed by the yeast’s membrane binds to the spike glycoprotein present on the external surface of the virus.

“The yeast is normally beige. When this interaction takes place, the presence of the virus is signaled by a fluorescent green that can easily be detected by the equipment typically found in clinical analysis labs,” says Gleidson Silva Teixeira, one of BIOinFOOD’s partners.

Teixeira studied under Professor Gonçalo Amarante Guimarães Pereira, who leads one of the laboratories at UNICAMP’s Institute of Biology, where the idea came up. According to the researchers’ expectations, the new test will be both fast and cheaper than RT-PCR because of the low cost of yeast, the main input.

Another important difference is that it will probably use saliva. Being non-invasive is an advantage for . Many people experience intense discomfort when undergoing collection of their material by nasal swab.

The sensitivity of the test is expected to be high, meaning it will be able to detect the virus only a few days after infection. “We plan eventually to have the yeast emit red light, which will be easier to identify,” Teixeira says. “In this case, anyone will be perfectly capable of using the test, even at home.”

Once the working hypothesis formulated in UNICAMP’s laboratories has been fully validated, the startup’s scientists expect the test to be brought to market and freely available for purchase during first-half 2021.

“The project is also supported by FINEP [the Brazilian government’s innovation agency] and must be developed rapidly because we can’t miss an opportunity to help combat the pandemic,” Teixeira says.

The idea of developing a product designed to combat COVID-19 arose from a call issued by FAPESP when the pandemic arrived in Brazil (in March 2020), inviting researchers in the state of São Paulo to submit proposals for creative solutions in this direction. “The secret, in this case, is genetic modification of the yeast,” Teixeira says. “We’re confident the hypothesis will work and the biosensor we’re constructing will emit a totally reliable signal.”

The raw materials for the product are simple and distribution of the diagnostic test should be logistically straightforward.

Bread and beer

The innovation involved in the COVID-19 diagnostic test came out of a technology mastered previously by BIOinFOOD, according to one of its owners. The startup offers a biotech platform based on S. cerevisiae, a versatile microorganism widely used in industry as a biofactory. Organic acids, amino acids, enzymes, and therapeutic proteins are some of the outputs of the platform.

“In the specific case of the technology used to develop the COVID-19 test, we want to see the platform being adapted to other types of disease in future,” Teixeira says.

The firm also develops custom yeasts for use by bakeries and breweries to suit consumer tastes. “We have several yeast-based solutions. Yeasts are well-known microorganisms. They can also be used in animal feed,” Teixeira says.

Startup develops yeast-based COVID-19 diagnostic test (2021, January 29)
retrieved 30 January 2021
from https://phys.org/news/2021-01-startup-yeast-based-covid-diagnostic.html

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